Determination of Pareto frontier in multi-objective maintenance optimization

The objective of a maintenance policy generally is the global maintenance cost minimization thatinvolves not only the direct costs for both the maintenance actions and the spare parts, but also thoseones due to the system stop for preventive maintenance and the downtime for failure. For someoperating systems, the failure event can be dangerous so that they are asked to operate assuring a veryhigh reliability level between two consecutive fixed stops. The present paper attempts to individuatethe set of elements on which performing maintenance actions so that the system can assure therequired reliability level until the next fixed stop for maintenance, minimizing both the globalmaintenance cost and the total maintenance time. In order to solve the previous constrained multiobjectiveoptimization problem, an effective approach is proposed to obtain the best solutions (that isthe Pareto optimal frontier) among which the decision maker will choose the more suitable one. As wellknown, describing the whole Pareto optimal frontier generally is a troublesome task. The paperproposes an algorithm able to rapidly overcome this problem and its effectiveness is shown by anapplication to a case study regarding a complex series–parallel system.